Authors: GÖKTUĞ ULUSU, MUSTAFA ERAT, MEHMET ÇİFTÇİ, HALİS ŞAKİROĞLU, EBUBEKİR BAKAN
Abstract: Glutathione reductase (Glutathione: NADP^+ oxidoreductase, EC 18.104.22.168; GR) was purified from sheep liver. The purification included 4 steps: preparation of homogenate, ammonium sulfate fractionation, 2', 5'-ADP Sepharose-4B affinity chromatography, and gel filtration chromatography. GR was obtained with a yield of 14.1% having a specific activity of 47.27 EU/mg proteins. Optimal pH, stable pH, and optimal temperature were 8.0, 5.5, and 60 °C, respectively. K_M and V_max values for NADPH and GSSG substrates were 0.0258 and 0.0239 mM, and 0.266 and 0.255 EU/ml, respectively. The overall purification was about 1477-fold for liver GR. The enzyme activity was measured spectrophotometrically at 340 nm. In addition, K_i values of 4.367 and 0.4055 mM were determined by means of Lineweaver-Burk graphs for NADP^+ and GSH, respectively.
Keywords: Glutathione reductase, purification, characterization, sheep, liver
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